Pressure differential lift device



Aug. 29, 1967 FOGG 3,338,615

PRESSURE DIFFERENTIAL LIFT DEVTCE Filed Oct. 18, 1965 2 Sheets-Sheet I ATTORNEYS Aug. 29, 1967 D. A. FOGG PRESSURE DIFFERENTIAL LIFT DEVICE 2 Sheets-Sheet 2 Filed Oct. 18, 1965 r i f Qdd INVENTOR. Q/QU/[Z A. [66

ATTORNEYS United States Patent 3,338,615 PRESSURE DIFFERENTIAL LIFT DEVICE Daniel A. Fogg, White Cloud, Mich, assignor to Rapistan Incorporated, a corporation of Michigan Filed Oct. 18, 1965, Ser. No. 497,351 Claims. (Cl. 294-64) This invention relates to apparatus for hoisting and transferring articles, and more particularly to a pressure differential lifting apparatus for hoisting and shifting groups of articles such as cartons. Such equipment is frequently termed palletizing apparatus by those familiar with this field.

Vacuum or suction type lifting heads of various types have been employed heretofore in the palletizing field. These devices are all fairly closely related, and employ a hollow vacuum head with an orificed underside to fit against the top of cartons to be hoisted, and either pneumatic eripheral cushions to abut the corners of the cartons or flexible flaps to extend around the side walls of the cartons, and form a tight seal. These curtain flaps or resilient cushions constitute a real nuisance during alignment of the lifting head with the carton. The curtains or cushions must correspond closely to the carton pattern periphery. For example, if the space tolerance between the curtains and carton edges are not very close, the curtains will not pull up against the cartons during initial evacuation, to seal. Even with closed fitting curtains or cushions, a slight misalignment of the cartons, or a gap in the pattern of cartons to be hoisted, can prevent effective evacuation by the lifting head with present equipment.

Also, since the spacing of the curtains or resilient pads must be selected to exactly suit a particular size and configuration carton pattern, the lifting head can normally only conveniently accommodate one particular size and shape of group of cartons.

It is an object of this invention to provide a novel pressure differential lift device of a dynamic flow type that is not dependent on obtaining an air-tight seal around a group of items such as cartons in order to effectively lift them. No curtains, resilient pads or the equivalent are necessary or employed to form an air seal.

It is another object of this invention to provide a pressure differential lift device employing constant dynamic air flow to achieve the actual lifting force. No seal is formed. Rather air can and does flow constantly and at high velocities over the upper surfaces of the items.

Another object of this invention is to provide a dynamic, pressure differential lift device that can hoist groups of cartons or other items, whether or not they are in a closely assembled, tightly packed group. The apparatus can even hoist a group of cartons having an opening pocket or gap within the pattern.

Another object of this invention is to provide a dy namic air flow, pressure differential, lift device capable of hoisting groups of cartons or other items having different overall pattern widths, lengths, and configurations. The pattern dimensions need not be limited to specific widths or lengths. Ratherthe pattern can vary substantially.

These and other objects of this invention will become apparent upon studying the following specification in conjunction with the drawings in which:

FIG. 1 is a perspective view of the upper portion of the novel lift head device shown suspended as on a hoist;

FIG. 2 is a bottom view of the underside of the lifting platform;

FIG. 3 is a fragmentary perspective view of a portion of the apparatus in FIG. 1, taken in the direction indicated by the arrow III in FIG. 1;

3,338,615 Patented Aug. 29, 1967 FIG. 4 is a fragmentary sectional view of the apparatus in FIG. 2 taken on plane IV-IV;

FIG. 5 is a fragmentary enlarged view taken on plane VV of FIG. 2, showing the device hoisting a plurality of cartons; and

FIG. 6 is a fragmentary sectional view of a modified form of the platen head, showing a different type of undersurface.

The complete lifting unit assembly 10, includes a hollow lifting head platform 12 subassembly, and a dynamic pressure differential producing subassembly 14. The latter includes an upright electrical motor 16 having its output shaft operably connected to a centrifugal blower unit 18.

Platform lift head subassembly 12 comprises a pair of spaced panels, i.e., upper horizontal panel 22 and lowerhorizontal panel 24. These are peripherally connected by a peripheral wall 26 to form a chamber 28. The chamber has an internal negative pressure during operation, created by the blower. The blower is of the centrifugal type, having a plurality of revolving blades in normal fashion,

a central inlet port 22' from chamber 28 (FIG. 5), anda tangential outlet exhaust port 30 (FIG. 1). This blower is anchored to the upper surface of platform 22, as is motor 16, by being mounted to a suitable superstructure framework 34. This framework includes a plurality of four upright columns 36 interconnected by cross beams 38 to which the motor is secured. On the upper ends of columns 36 are suitable connectors 40 for connection to hoisting chains 42 or the equivalent.

Electrical motor 16 is operated through a suitable electrical assembly in housing 50, employing a hand held control box 52 electrically connected to this assembly through a suitable electrical conduit 54. The electrical system may include a suitable transformer 56. The details of this control apparatus could be modified in a great many ways, as will be apparent upon studying the function of the device as described hereinafter.

Exhaust port 30 from the centrifugal blower is controlled by a pivotal butterfly valve 60 mounted on a transverse central pivot shaft 62. Closure of this valve creates back pressure within the blower to release the negativepressure from platform head 28, thereby causing release of articles on the underside in .a manner to be described hereinafter. This butterfly valve may be pivoted on its shaft between open and closed positions by a solenoid and 72 on one end, and connected to a tension coil spring 74 on the other end. Coil spring 74 is secured to a suitable cross beam 78. The solenoid 72 is also suitably affixed to this cross beam. Retraction of solenoid armature 70 into the windings of solenoid 72 pulls the chain to pivot butter fly valve 60 and closes off exhaust port 30. Release ofthe solenoid causes opening of the valve by retraction of chain 68 with tension spring 74.

The lower lift head panel 24 includes a plurality of elongated slot shaped orifices, each having a length many times greater than the width. These are arranged in concentric, generally square as patterns illustrated in FIG. 2.

More specifically, a first set of slots is'arranged in a concentric rectangular or square pattern, a second set of.

elongated slots 82 is arranged around slots 80 in a like pattern with a larger spacing, and a third set of slots 84 1 is arranged concentrically around the second set. These orifices are in elongated slot form since this has been found preferable for dynamic flow as explained more fully hereinafter.

Although three sets of slots are illustrated, more or less may be employed as deemed necessary. Preferably;

. (a the device is provided with gate means to open or close selected sets of slots for varying the overall platform area to be covered by contacted cartons. If the outer slots are not covered by cartons, they should be closed to prevent needless excess air flow.

If the outermost slots are not employed, therefore, because a pattern of cartons is smaller than these dimensions, they are closed with slidable gates, here shown to be a plurality of four sliding gates 90a, 90b, 90c, and 90d operated by handles 98a, 98b, 98c, and 98d, respectively. These are mounted along the four edges of the panel to be slidable therebeneath as shown in FIGS. 2, 4 and 5.

Slide 9% is shown retracted from its normal cover position over slots 84 to illustrate the operation thereof.

Each of the slides may be retained by a suitable pair of Z-shaped slide brackets, i.e. 96a, 96b, 96c, and 960! respectively. The sliding gate members are shown to be able to cover only or uncover the third set of slots, it Will be realized that gates covering more than one set of slots may be provided, if necessary.

The undersurface of this lift head assembly is variegated to effect a great number of narrow fiow passages. In the first form of the device, this is obtained with a sheet of expanded metal 106 which extends over the entire area of the slot patterns, and over the undersurface areas of sliding gate members 90a. through d as illustrated in FIGS. 2 and 5. This sheet of expanded metal is corrugated and orificed in conventional fashion so that the air can flow through the corrugations in a manner similar to that illustrated in FIG. 5. Its thickness is only a fraction of an inch so that the depth between the upper surfaces of cartons e.g. C1 and C2, and the lower surface of orificed plate 24 is only a fraction of an inch. This expanded metal may be attached to this undersurface in any suitable manner such as by tack welding or the equivalent. (In FIG. 2, for purposes of clarity, the complete pattern of reticulated expanded metal is not shown over its entire dimensions in order to enable the slots to be more clearly seen.) The purpose of the expanded metal is to retain the carton surface at a definite but small controlled spacing from the platform undersurface. This is to cause a constant, dynamic, and high velocity air flow between the cartons and platform undersurface. The cartons must be spaced sufliciently to allow constant air flow over substantially their entire upper surface area. Yet the spacing cannot be very large since high velocity is important to obtain a pressure differential according to Venturi flow principles. The elements necessary to space the cartons should be minimized in carton area coverage, so that maximum air flow area is effected. Obviously, therefore, other means besides the expanded metal will effectively meet these conditions and requirements.

The operation of this novel assembly uses dynamic air flow, in contrast to generally static conditions employed by previous constructions. That is, instead of a tight seal being created between the cartons or other articles and the lift unit as is achieved with the curtains, pressure pads, and the equivalent appendage of prior units, a dynamic high velocity air flow occurs constantly across the upper surface area of the cartons. The blower assembly 18 draws air out of the negative pressure chamber 28 through opening 22' and projects it out exhaust 30. This draws air through the narrow passage area across the upper surfaces of the cartons and through elongated slots 80, 82 and 84. It has been found that this creates a tremendous lifting force on the bottoms of the cartons as indicated by the arrow F in FIG. 5, because of the pressure differential between atmospheric pressure beneath and negative pressure in the high velocity area where a substantial pressure drop occurs. Cartons or other suitable articles of substantial weight can therefore be readily hoisted in a safe reliable manner and shifted from one position to another. Release of the articles is achieved instantly by closing exhaust valve 60, thereby stopping the air flow and releasing the negative pressure across the upper surfaces of the cartons. It has been found that the velocity should be maximized in the area over the surfaces of the cartons for concomitant minimum pressure, but that the pressure drop across the orifices in panel 24 should be minimized. These orifices are therefore preferably made of elongated slotted configuration since this has been found to provide maximum air volume flow through panel 24, but still keep the orifices in controlled patterns. It will be apparent that each slot may instead be a series of small orifices or the equivalent, within the broader aspects.

If the pattern of cartons to be hoisted overlap only slot patterns and 82, the outer set of slots 84 is covered by sliding the four gate members a-90d toward the center to the positions illustrated in gates 99a, 90c and 90d in FIG. 2. If, however, a larger pattern is to be accommodated the gates are slid out from the covering position of slots 84, e.g. like gate 901) in FIG. 2.

It is important to note that the dimensions and configuration of varying patterns of cartons are not critical as they are with previous units. Rather reasonable pattern configuration and size variations can be readily accommodated.

Experimentation has shown that, although the expanded metal 106 Works very effectively, other suitable equivalents on the lower panel surface can be employed as long as a thin air flow area is created over the surfaces of the cartons to achieve the high velocity air flow across the carton tops. Referring to FIG. 6 one example of a variation is shown by the modified lower panel 124 which has a plurality of small integral protrusions 126 to contact and space cartons e.g. C11 and C12 to form a narrow high velocity passage area between the main panel surface and the carton surfaces for flow from the surrounding atmosphere to orifices 180, etc This modified assembly includes a blower suba-ssembly 18 like that in previous figures, combined with lifting platform 112 having upper panel 122 and modified lower panel 124. The plurality of elongated slots 180, etc. in panel 124 are like those illustrated in FIG. 2.

Operation The complete operation of the apparatus will be readily apparent from the previous description of the structure. Depending upon the size of the carton pattern to be hoisted, gates 9041-900! may be extended to uncover slots 84 or contracted to cover these slots. The blower is then started using electrical controls to the electrical motor 16 to rotate centrifugal blower 18 at a high rate of speed. This draws air from negative pressure chamber 28 up through opening 22 of platform 22 through the blower and then out exhaust port 30. When articles are to be hoisted, the lower surface of the assembly is placed against the carton pattern, with valve 60 closed. When the platform is properly aligned with the pattern of cartons, valve 60 is opened by electrically releasing armature 70 of solenoid 72, allowing tension spring 74 to retract chain 68 and thereby pivot the gate valve open. This causes an immediate negative pressure in chamber 28, causing a tremendous high velocity of gaseous flow through the narrow space between' the carton patterns and the platform undersurface, and into orifices 80, 82, etc. The high velocity is accompanied by a negative pressure which causes a lifting pressure differential. This differential is applied to the bottoms of the cartons if the tops of the cartons have openings. If the tops of the cartons are sealed, the hoisting differential is across the entire carton height. After the cartons are hoisted and transferred to a desired position, they are released instantly merely by activating solenoid 72 to retract its armature 70 and shift valve 60 closed. This destroys the negative pressure in chamber 28, stops the flow of high velocity air across the tops of the cartons, and thereby destroys the lifting force.

It is conceivable that certain additional obvious modifications in the construction of the dynamic flow lifting apparatus may be made within the concept presented herein. Hence, the invention is not intended to be specifically limited to the preferred forms of the apparatus illustrated, but only by the scope of the appended claims and the reasonably equivalent structures to those defined therein.

I claim:

1. Pressure differential article lifting apparatus capable of hoisting substantial loads such as filled cartons and the like, comprising: a hoistable lift platform having an article engaging under surface area; air flow ports in said platform at spaced intervals in a pattern over said under surface area, spaced inwardly from the outer periphery of said area; air blower means operatively associated with said platform, having inlet means communicant with said ports to draw air therethrough; article engaging means over the under surface area of said platform, spaced from said air flow ports to prevent blocking of said ports by engaged articles, and forming a labyrinth of a large number of shallow, high velocity air passage means from the outer periphery of said area, between said under surface area and adjacent article surfaces, to said ports; said hollow air passage means allowing constant high velocity air flow from said area periphery between the article surfaces and said under surface area and then through said ports to said blower means, to create a hoisting pressure differential by a dynamic venturi flow lift action on articles covering said area; and means to arrest flow through said blower means to destroy said dynamic venturi flow lift action, for controllably releasing articles from said lifting apparatus.

2. The apparatus in claim 1 wherein said ports are arranged in a pattern, and including means to selectively close certain of said ports to vary the effective hoisting area of said platform for accommodating variously sized /and configurated patterns of articles to be hoisted.

3. The apparatus in claim 2 wherein said ports are of elongated, slot type configuration, arranged in rectangular patterns at spaced intervals from the center of said platform, and said port closing means comprises a plurality of slidable gates.

4. The apparatus in claim 1 wherein said article engaging means comprises reticulated, open mesh, three dimensionally expanded sheet means over said underside area.

5. The apparatus in claim 1 wherein said article engaging means comprises a plurality of spaced protrusions over said underside area.

References Cited UNITED STATES PATENTS 3,158,367 11/1964 Tarbuck 294-64 3,259,417 7/1966 Chapman 294-64 GERALD M. FORLENZA, Primary Examiner.

G. F. ABRAHAM, Assistant Examiner. 

1. PRESSURE DIFFERENTIAL ARTICLE LIFTING APPARATUS CAPABLE OF HOISTING SUBSTANTIAL LOADS SUCH AS FILLED CARTONS AND THE LIKE, COMPRISING: A HOISTABLE LIFT PLATFORM HAVING AN ARTICLE ENGAGING UNDER SURFACE AREA; AIR FLOW PORTS IN SAID PLATFORM AT SPACED INTERVALS IN A PATTERN OVER SAID UNDER SURFACE AREA, SPACED INWARDLY FROM THE OUTER PERIPHERY OF SAID AREA; AIR BLOWER MEANS OPERATIVELY ASSOCIATED WITH SAID PLATFORM, HAVING INLET MEANS COMMUNICANT WITH SAID PORTS TO DRAW AIR THERETHORUGH; ARTICLE ENGAGING MEANS OVER THE UNDER SURFACE AREA OF SAID PLATFORM, SPACED FROM SAID AIR FLOW PORTS TO PREVENT BLOCKING OF SAID PORTS BY ENGAGED ARTICLES, AND FORMING A LABYRINTH OF A LARGE NUMBER OF SHALLOW, HIGH VELOCITY AIR 